In the field of the driving control of a vehicle, such as an automobile, there have been proposed various types of driving support systems and/or automatic driving systems to control a steering mechanism and/or an accelerating-decelerating mechanism of a vehicle so that a driver can drive the vehicle more easily. For instance, in the Lane Keeping Assist (LKA) control, in order to prevent a running vehicle from deviating from its lane, a caution is given to a driver with a warning buzzer, etc., when the vehicle is likely to deviate from its lane. Further, in a radar cruise control, a steering support for a driver is performed to execute a speed control which maintains a vehicle speed to a set speed without depressing an accelerator pedal while making the vehicle running along a lane. Also, in the Intelligent Parking Assistant (IPA), a steering support is performed in parallel parking or vehicle garaging. Moreover, in patent document 1, there is disclosed a structure in which, in conducting a lane change of a running vehicle, the steering reaction force of a handle is changed so as to bring the actual steering angle close to an optimal steering angle computed based on circumference environment information, thereby making it easy for a driver to adjust the steering angle to the optimal steering angle. Patent document 2 discloses one manner for driving support in which a target steering angle is determined based on circumferential information of a vehicle, and a steering assist force is increased in the same direction as the target steering angle and decreased in the opposite direction to the target steering angle. Furthermore, patent document 3 discloses a structure of driving support in which a lateral acceleration compensation amount for making a vehicle go to a target position determined using an image of an in-vehicle camera is computed out while the magnitude of a driver's steering amount is detected, and when the steering amount is smaller than a predetermined threshold value, a steering control is performed after slowing down the vehicle so that the lateral acceleration compensation amount may be achieved, and, when the steering amount is larger than the predetermined threshold value, the vehicle is slowed down after performing a steering control so that the lateral acceleration compensation amount may be achieved.